12:57 AM
3

I am a bit confused as to what I should use to derive the equations of motions from the lagrange equation. Suppose I have a lagrange function: $$L(x(t), \dot{x}(t)) = \frac{1}{2}m\dot{x}^2-\frac{1}{2}k(\sqrt{x^2+a^2}-a)$$ Method 1: Principle of least action \delta L = \delta \dot{x}(m\dot{x...

6 hours later…
7:06 AM
1

I am not asking about whether the photon goes through both slits, or why. I am not asking whether the photon is delocalized as it travels in space, or why. I have read this question: Do we really know which slit the photon passed through in Afshar's experiment? Which theory explains the path o...

1 hour later…
8:07 AM
6

We were taught at school that EM radiation can be categorised as radio waves, microwaves, infrared waves, visible light, ultraviolet radiation, X-rays, and gamma rays, but how arbitrary is this categorisation? I understand that for humans the 'visible light' category is an obvious, but how did s...

12 hours later…
8:01 PM
1

I can't say I know physics very well. The most confusing concept for me as for now is potential energy. Often, when introducing potential energy of a gravitational force, the following example is used: imagine an object that has the mass of 1 kilogram that is lying on the earth. The gravitational...